Converter DC bus capacitor resonant frequency detection device

Abstract

The utility model discloses a converter DC bus capacitor resonant frequency detection device comprising an adjustable DC power supply assembly, a discharge unit, a detected capacitor group and a detection device. The output end of the adjustable DC power supply assembly is connected with the input end of the discharge unit, the output end of the discharge unit is connected with the detected capacitor bank, and the detection device comprises a current loop and an oscilloscope; the tested capacitor bank comprises a capacitor bank, a positive copper bar Bus + and a negative copper bar Bus-; the positive copper bar Bus + and the negative copper bar Bus-are connected with the output end of the discharge unit; the capacitor bank is composed of a plurality of capacitor monomers connected in parallel between the positive copper bar Bus + and the negative copper bar Bus-, the test end of the current loop is installed at any end of the capacitor monomers, and the oscilloscope is connected with the other end of the current loop; the device can measure the resonant frequency of the measured DC bus capacitor bank under the condition that only hardware is adopted, the risk of resonance of the DC bus capacitor is reduced, and the situation of over-temperature failure of the DC bus capacitor is reduced.

Description

Technical Field

[0001] The utility model relates to the field of measurement technology, in particular to a converter DC bus capacitor resonant frequency detection device. Background Art

[0002] With the application of high-power converters, the design of the DC bus link, including the design of the laminated busbar inductance, the connection between the laminated busbars, and the selection of the single DC busbar capacitance, has become increasingly important. If a single-phase power module is used, three sets of DC busbar capacitors need to be connected, and the connection will generate considerable stray inductance. The stray inductance generated by these connections and the stray inductance inside the laminated copper busbar are at risk of resonating with the DC busbar capacitor. A large resonant current will cause the DC busbar capacitor to overheat and fail.

[0003] The DC bus capacitor resonant frequency detection in the prior art is mainly concentrated on the software level such as algorithm and control, attempting to reduce or suppress harmonic current from the software control or wave generation aspect. There is a lack of devices for detecting the resonant frequency of the converter DC bus capacitor from the perspective of hardware design or from the perspective of preliminary designed DC bus hardware detection. Utility Model Content

[0004] The technical problem to be solved by the utility model is to propose a converter DC bus capacitor resonant frequency detection device, which can measure the resonant frequency of the DC bus capacitor group under the condition of only using hardware, reduce the risk of resonance of the DC bus capacitor, and reduce the occurrence of over-temperature failure of the DC bus capacitor.

[0005] In order to solve the above technical problems, the utility model provides a converter DC bus capacitor resonant frequency detection device, including an adjustable DC power supply component, a discharge unit, a capacitor group to be measured and a detection device;

[0006] The output end of the adjustable DC power supply component is connected to the input end of the discharge unit, the output end of the discharge unit is connected to the capacitor group to be tested, and the detection equipment includes a current loop and an oscilloscope;

[0007] The measured capacitor group includes a capacitor group, a positive copper bus Bus+, and a negative copper bus Bus-;

[0008] The positive copper busbar Bus+ and the negative copper busbar Bus- are connected to the output end of the discharge unit;

[0009] The capacitor group is composed of a plurality of capacitor monomers connected in parallel between the positive copper bus Bus+ and the negative copper bus Bus-. The test end of the current loop is installed at either end of the capacitor monomer, and the oscilloscope is connected to the other end of the current loop.

[0010] Preferably, the adjustable DC power supply assembly comprises an adjustable DC power supply Vs and a first contactor KM;

[0011] The first port of the adjustable DC power supply Vs is connected to the first port of the first contactor KM.

[0012] Preferably, the discharge unit includes a voltage indicator V, a controllable switch T, a second contactor KM1, a first resistor R1, and a second resistor R2;

[0013] The first port of the voltage indicator V is connected to the second port of the first contactor KM, and the second port is connected to the second port of the adjustable DC power supply Vs; the first port of the controllable switch T is connected to the second port of the first contactor KM, and the second port is connected to the first port of the first resistor R1; the second port of the first resistor R1 is connected to the second port of the adjustable DC power supply Vs; the first port of the second contactor KM1 is connected to the second port of the first contactor KM, and the second port is connected to the first port of the second resistor R2; the second port of the second resistor R2 is connected to the second port of the adjustable DC power supply Vs.

[0014] Preferably, the positive copper bus Bus+ is composed of a complete copper bus or multiple sections of copper bus, and the multiple sections of copper bus are connected by switching copper bus or cables; the negative copper bus Bus- is composed of a complete copper bus or multiple sections of copper bus, and the multiple sections of copper bus are connected by switching copper bus or cables; the several capacitor monomers include one of capacitor monomer c1, capacitor monomer c2, ..., capacitor monomer cm, ..., capacitor monomer cn, or a parallel combination thereof.

[0015] After adopting the above device, the converter DC bus capacitor resonant frequency detection device includes an adjustable DC power supply component, a discharge unit, a measured capacitor group and a detection device; the output end of the adjustable DC power supply component is connected to the input end of the discharge unit, the output end of the discharge unit is connected to the measured capacitor group, and the detection device includes a current loop and an oscilloscope; the measured capacitor group includes a capacitor group, a positive copper bar Bus+, and a negative copper bar Bus-; the positive copper bar Bus+ and the negative copper bar Bus- are connected to the output end of the discharge unit; the capacitor group is composed of a plurality of capacitor monomers connected in parallel between the positive copper bar Bus+ and the negative copper bar Bus-, the test end of the current loop is installed at either end of the capacitor monomer, and the oscilloscope is connected to the other end of the current loop; the converter DC bus capacitor resonant frequency detection device can measure the resonant frequency of the measured DC bus capacitor group under the condition of only using hardware, reduce the risk of resonance of the DC bus capacitor, and reduce the occurrence of over-temperature failure of the DC bus capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is an overall circuit diagram of the converter DC bus capacitor resonant frequency detection device.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Embodiment 1

[0020] See also Figure 1 , Figure 1 The overall circuit diagram of the converter DC bus capacitor resonant frequency detection device of the utility model;

[0021] This embodiment discloses a converter DC bus capacitor resonant frequency detection device, including an adjustable DC power supply component 10, a discharge unit 20, a capacitor group to be measured 30 and a detection device;

[0022] The output end of the adjustable DC power supply component 10 is connected to the input end of the discharge unit 20, and the output end of the discharge unit 20 is connected to the capacitor group 30 to be tested. The detection equipment includes a current loop I1 and an oscilloscope OSC;

[0023] The capacitor group 30 to be tested includes a capacitor group, a positive copper bus Bus+, and a negative copper bus Bus-;

[0024] The positive copper bus Bus+ and the negative copper bus Bus- are connected to the output end of the discharge unit 20;

[0025] The capacitor group is composed of a plurality of capacitor monomers connected in parallel between the positive copper bus Bus+ and the negative copper bus Bus-. The test end of the current loop I1 is installed at either end of the capacitor monomer, and the oscilloscope OSC is connected to the other end of the current loop I1. Embodiment 2

[0026] This embodiment is based on the first embodiment. In this embodiment, the adjustable DC power supply assembly includes an adjustable DC power supply Vs, a first contactor KM;

[0027] The first port of the adjustable DC power supply Vs is connected to the first port of the first contactor KM. Embodiment 3

[0028] This embodiment is based on the first embodiment. In this embodiment, the discharge unit 20 includes a voltage indicator V, a controllable switch T, a second contactor KM1, a first resistor R1, and a second resistor R2;

[0029] The first port of the voltage indicator V is connected to the second port of the first contactor KM, and the second port is connected to the second port of the adjustable DC power supply Vs; the first port of the controllable switch T is connected to the second port of the first contactor KM, and the second port is connected to the first port of the first resistor R1; the second port of the first resistor R1 is connected to the second port of the adjustable DC power supply Vs; the first port of the second contactor KM1 is connected to the second port of the first contactor KM, and the second port is connected to the first port of the second resistor R2; the second port of the second resistor R2 is connected to the second port of the adjustable DC power supply Vs.

[0030] In this embodiment, a driving signal is provided to the controllable switch T for a period of time, and the controllable switch T is continuously closed. The measured capacitor group 30 will discharge to the first resistor R1, and a step-like voltage will be generated in the power circuit of the measured capacitor group at the moment when the driving signal is turned off. This voltage contains a large amount of frequency signals and will generate continuous excitation between the load capacitor group and the stray inductance.

[0031] The voltage indicator V is used to observe the voltage of the load capacitor group. During the detection of the resonant frequency, it is necessary to ensure that the voltage indicator V is always greater than zero. The second contactor KM1 and the second resistor R2 discharge the load capacitor group after the resonant frequency detection is completed. Embodiment 4

[0032] This embodiment is based on the first embodiment. In this embodiment, the positive copper bus Bus+ is composed of a complete copper bus or a plurality of copper bus sections, and the plurality of copper bus sections are connected by transfer copper bus sections or cables; the negative copper bus Bus- is composed of a complete copper bus or a plurality of copper bus sections, and the plurality of copper bus sections are connected by transfer copper bus sections or cables; the plurality of capacitor monomers include one of capacitor monomer c1, capacitor monomer c2, ..., capacitor monomer cm, ..., capacitor monomer cn, or a parallel combination thereof.

[0033] The current loop I1 is installed on the capacitor monomer under test, and the resonant frequency of the capacitor group under test is read through the oscilloscope OSC. Different capacitor monomers correspond to different resonant circuits and have different resonant frequencies.

[0034] The converter DC bus capacitor resonant frequency detection device can measure the resonant frequency of the DC bus capacitor group under the condition of using only hardware, reduce the risk of resonance of the DC bus capacitor, and reduce the occurrence of over-temperature failure of the DC bus capacitor.

[0035] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the present application is not limited thereby. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application shall be within the scope of the present application.

Claims

1. A converter DC bus capacitor resonant frequency detection device, characterized in that: It includes an adjustable DC power supply component, a discharge unit, a capacitor group to be tested and a detection device; The output end of the adjustable DC power supply component is connected to the input end of the discharge unit, the output end of the discharge unit is connected to the capacitor group to be tested, and the detection equipment includes a current loop and an oscilloscope; The measured capacitor group includes a capacitor group, a positive copper bus Bus+, and a negative copper bus Bus-; The positive copper busbar Bus+ and the negative copper busbar Bus- are connected to the output end of the discharge unit; The capacitor group is composed of a plurality of capacitor monomers connected in parallel between the positive copper bus Bus+ and the negative copper bus Bus-. The test end of the current loop is installed at either end of the capacitor monomer, and the oscilloscope is connected to the other end of the current loop.

2. The converter DC bus capacitor resonant frequency detection device according to claim 1, characterized in that: The adjustable DC power supply assembly includes an adjustable DC power supply Vs and a first contactor KM; The first port of the adjustable DC power supply Vs is connected to the first port of the first contactor KM.

3. The converter DC bus capacitor resonant frequency detection device according to claim 2, characterized in that: The discharge unit includes a voltage indicator V, a controllable switch T, a second contactor KM1, a first resistor R1, and a second resistor R2; The first port of the voltage indicator V is connected to the second port of the first contactor KM, and the second port is connected to the second port of the adjustable DC power supply Vs; the first port of the controllable switch T is connected to the second port of the first contactor KM, and the second port is connected to the first port of the first resistor R1; the second port of the first resistor R1 is connected to the second port of the adjustable DC power supply Vs; the first port of the second contactor KM1 is connected to the second port of the first contactor KM, and the second port is connected to the first port of the second resistor R2; the second port of the second resistor R2 is connected to the second port of the adjustable DC power supply Vs.

4. The converter DC bus capacitor resonant frequency detection device according to claim 1, characterized in that: The positive copper bus Bus+ is composed of a complete copper bus or multiple copper bus sections, and the multiple copper bus sections are connected by transfer copper bus sections or cables; The negative copper bus Bus- is composed of a complete copper bus or multiple sections of copper bus, and the multiple sections of copper bus are connected by switching copper buses or cables; the plurality of capacitor monomers include one of capacitor monomer c1, capacitor monomer c2, ..., capacitor monomer cm, ..., capacitor monomer cn or a parallel combination thereof.

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